CVE-2026-30913 flarum/nickname: Display name injection in notification emails (autolink & markdown)
Attackers can inject malicious links into notification emails via nicknames, misleading users to visit attacker-controlled domains.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-30913?
CVE-2026-30913 is a medium-severity cross-site scripting vulnerability in flarum nicknames, published on 9 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Flarum is open-source forum software. When the flarum/nicknames extension is enabled, a registered user can set their nickname to a string that email clients interpret as a hyperlink. The nickname is inserted verbatim into plain-text notification emails, and recipients may be misled into visiting attacker-controlled domains.
Weakness: CWE-79
Which versions are affected by CVE-2026-30913?
2 open source packages ship an affected version, including flarum/nicknames.
| Package | Affected | Fixed in |
|---|---|---|
flarum/nicknames Packagist | All versions | 1.8.3 |
flarum/nicknames Packagist | All versions | 1.8.3 |
How do I fix CVE-2026-30913?
Upgrade flarum/nicknames to 1.8.3 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-30913 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-30913 exists.
Sources
Also known as GHSA-3c4m-j3g4-hh25.